Keyhole plug



April 21, 1925.

1,534,745 n J. STAPLETON KEYHOLE PLUG Filajna. 2, 1921y F76- l. u v i F76. Z.

/NVENTOR A Trvs.

Patented Apr. 21, 1925.

j'UNiTED STATES 1,534,745 PATENT o1`=pFlc1a:

JEBNY STAPLETON, F LOS ANGELES, CALIFORNIA, ASSIGNOR 0F ONE-HALF T0 DAVID A. FLEMING, 0F LOS ANGELES, CALIFORNIA.

' KEYHOLE PLUG.

Application mea December 2s, 1921. serial Ne. 525,655.

Tio all whom tmay concern Be it known that I, JERRY STAPLETON, a citizen of the United States, residing Vat Los Angeles,in the county of Los Angeles and State of California, have invented new and .useful Improvements in=Keyhole Plugs, of whichthe following is a specification.

My invention relates to door locks, and a purpose of my invention is the provision of l0 akeyhole plug adapted for application to the keyhole of a lock to prevent the insertion of a key or instrument thereinto whereby the surreptitious operation of the lock is prevented.

I will describeone form of keyhole plug embodying my invention and will thenpoint ,out the novel features thereof in claims.

In the accompanying drawings,

l Figure 1 is a Vfragmentary view showing in edgeelevation a door with a conventional form of lock applied thereto, and having applied to the latter one form of keyhole plilig embodying my invention.

Iv ig. 2 is a view taken at right angles to Fig. 3 is a longitudinal sectional View of ,the plug shown in the preceding views with the operating key removed therefrom.

Figs. 4, 5 and 6 are transverse sectional views taken on the lines /1-4, 5-5 and 6 6, respectively, of Fig. 3.

Fig. 7 is a detail perspective View of the shank comprised in the plug shown in the preceding views.

Similar reference characters refer to similar parts in each of the several views.

Referring to the drawings my invention `in its present embodiment essentiallyy consists of a barrel B having `a depending radially arranged flange F, and with a shank S rotatably fitted in the barrel and movable to dispose a locking extension E in locking Jor releasing position with respect to a lock in effecting the securing of the plug within a keyhole or permitting the removal thereof. A key K is employed for actuating the shank S and a locking block L is associated with a shank for maintaining the same in locking position with respect to the locking extension E.

As clearly shown in Fig. 7, the shank S is of tubular form and is provided with a longitudinal extending slot 15 adapted for the reception of the key K. Within the length of the slot transverse slots 16 and 17 are formed in the shank, while at the bottom side of the shank and at opposite sides of the slot 16 recesses 18 and 19 are formed. As shown in Fig. 3, limiting pins 20 and 21 project inwardly from the inner side of the barrel B and are adapted to work in the slots 16 and 17 respectively for limiting the rotational movement of the shank S in either direction within the barrel. Wards 22 and 23 extend inwardly from the barrel B and are adapted to work in the recesses 18 and 19, respectively of the shank S. These wards are designed for the purpose of co-operating with clefts 24 and 25 formed in the key K in allowing turning movement of the key to effect a rotation of the shank S. It is to be noted that there are two clefts 24 to accommodate two wards 22 arranged in the manner indicated in dotted lines in Fig. 5.

A locking block L is shown as slidably fitted within the slot 15 of the shank S and is engaged by a coiled expansible spring 26 housed within the shank and normally urging the block into engagement with a pin 27 carried by the shank S and engaging the block within a recess 28. The tension of the spring 26 is such that the block is yieldingly maintained in engagement with the pin 27, and in this position a recess 29 formed in the upper edge of the block is disalined with respectto the limiting pin 21 so that rotation of the shank within the barrel is prevented. By moving the block L rearwardly against the tension of the spring 26, the recess 29 can be moved into registration with the pin 21 thereby allowing of the rotational movement of the shank.

In the operation of the plug, it is inserted into the keyhole to occupy the position shown in Figs. 1 and 2, it being understood 95 that the shank S is so positioned with respect to the barrel that the locking extension E is in vertical position or vertically alined with respect to the flange F, as clearly shown in Fig. 5. By inserting the key K into the 100 slot 15 of the shank S and forcing the same rearwardly causes the locking block L to be moved rearwardly against the tension of the spring 26 until it abuts the end of the slot 15, whence the recess 29 is in registration 105 with the pin 21. By maintaining this inward pressure on the key and then turning the same to the left as when viewed in Fig.

5, the shank can be rotated until engaged by the limit pin 20 when the locking eXten- 110 sion E will be in horizontal position as shown in Fig. 4. In this position of the locking extension, it engages the under side of the lock casing thus preventing Withdrawal of the plug and thereby serving to completely till the keyhole and prevent insertion of any instrument or key in attempting to effect an operation of the lock.

It is to be particularly noted that ras illustrated in F ig. 5, the arrangement of Wards is such as to permit Withdrawal of the key only when the locking extension is in horizontal or locking position. This obviously eliminates the possibility of the key being accidently Withdrawn without the plug securely locked Within the keyhole.

Although I have herein shown and described only one form of keyhole plug embodying my invention, it is to be understood that various changes and modifications may be made herein Without departing from the spirit of the invention and the spirit and scope of the appended claims.

I claim as my invention:

1. A. keyhole plug comprising a barrel, a flange formed on the barrel, a shank rotatably sustained in the barrel, a locking eX- tens-ion formed on the shank, pins in the barrel for limiting the rotational movement of vsaid shank in either direction, a spring pressed locking block having a recess therein which is normally disalined With respect to one of said pins to prevent rotation of the `shank Within the barrel, Wards Within the barrel, and a key insertable within the shank and barrel for forcing the block to cause said recess to register With said pin and having cletts therein adapted for registration With said Wards whereby rotation of said shank can be effected. n

2. A keyhole plug comprising a barrel, a flange formed on the barrel, a shank rotatably sustained in the barrel, a locking extension formed on the shank, means in the barrel for limiting the rotational movement ot said shank in either direction, a locking block having a recess therein Which is normally disalined with respect to said means to prevent rotation of the shank Within the barrel, Wards Within the barrel, and a key insertable Within the shank and barrel for moving the block to cause said recess to register with said means and having clefts therein adapted for registration with said Wards whereby rotation of said Vshank can be eiiected. Y

In testimony whereof I have signed my name to this specilication.

JERRY STAPLETON 

